The Internet has become an increasingly important part of our everyday lives. Millions of people now access the Internet on a daily basis to shop for goods and services, obtain information of interest (e.g., movie listings), and to communicate with friends, family and co-workers (e.g., via e-mail). This demand for Internet access has created a need for high-speed techniques for transmitting data between homes, businesses, and other institutions. One such technique is ADSL.
ADSL allows for high-speed data signals and analog voice signals to be simultaneously transmitted and received over existing copper telephone lines. As illustrated in FIG. 1, ADSL divides up the available frequencies in a telephone line into a voiceband portion 110, an upstream data-band portion 120, and a downstream data-band portion 130. The voiceband portion 110 carries analog voice signals between the telephone company's central office and, for example, a customer's residence. The upstream data-band portion 120 carries data to be uploaded to the Internet from the customer's residence. The downstream data-band portion 130 carries data to be downloaded from the Internet to the customer's residence.
The lines carrying the ADSL transmissions to and from a customer's residence or business may be affected by transient noise that may result from bridge taps and line switching. This transient noise may increase the bit error rate of the ADSL transmissions to unacceptable limits. Telephone companies can often predict which lines will be affected by transient noise, but it is difficult to accurately predict transient noise characteristics, such as time of occurrence, rate of occurrence, amplitude in relation to the transmitted signal, duration, and the like. Therefore, it is difficult to eliminate transient noise using conventional telephone hardware and software devices.
As a result, telephone companies would often not use telephone lines that exhibited a great deal of transient noise for those ADSL services that are highly affected by transient noise (e.g., user datagram protocol video). The volume of and demand for ADSL service, however, is ever increasing.
Therefore, there exists a need for systems and methods that are capable of suppressing transient noise in ADSL transmissions.